Evaporative cooling is a process of cooling air using the latent heat of the evaporation of water by keeping air and liquid water in a thermodynamic relationship. Temperature of dry air can be lowered significantly when it is passed through liquid water and turns water into water vapor. In extremely dry conditions, evaporative cooling has an added benefit of introducing moisture into dry air. So the input of a evaporative cooling apparatus is hot and dry air, while the output of the apparatus is cooler and moist air, which greatly improves the comfort level for the occupants of the space that the apparatus is intended for.
Evaporative cooling apparatus is relatively simple, and the physical properties of various stages of the process are well measured and understood. With growing concerns for the environment and rising costs associated with energy consumption, however, there is a renewed interest in improving the efficiency of such devices. The current invention of a multi-layered evaporative media module intended for heat exchange apparatus improves the efficiency of evaporative cooling through its new design in the following five main areas.
First, the design of the present invention utilizes almost the entire volume of the cooling tower for heat exchange purpose. Typical evaporative cooling devices employs a water delivery system that occupies the space on top of the evaporative media, for example, as illustrated in patents U.S. Pat. Nos. 7,992,406, 7,765,827, 3,116,612, and 4,380,910. The present invention, however, comprises a novel liquid/water delivery system that is embedded within the evaporative media module, which then occupies the entire inner space of the cooling tower.
Second, the design of the present invention employs a novel liquid/water delivery system that delivers liquid/water onto each layer of the evaporative media module. Such a new system reduces the turbulence of interaction between air and liquid while maximizing surface area during the process of heat exchange. As illustrated in patents U.S. Pat. Nos. 7,992,406, 7,765,827, 3,116,612, and 4,380,910, a sprinkler system is often used by spraying water at various locations onto the evaporative media while passing air through the media at the same time. After water is released from the sprinklers, it is essentially in a free falling state, until it hits the surface of the evaporative media. The distribution of liquid/water in such a system is largely uneven, with the top layers of the evaporative media receiving the most amount of water, and much less so further down stream, thus results in unevenness in heat exchange itself. The present invention overcomes this problem of unevenness in the distribution of liquid/water, by calmly delivers liquid/water onto each layer of the evaporative media, and thus improves heat exchange efficiency.
Third, the present invention can be configured as either a parallel flow or as a counter flow heat exchanger, by simply reversing the air cycle. There are two primary classifications of heat exchange according to their flow arrangement. In a parallel-flow situation, air and liquid enter the exchanger from the same end, and travel in parallel to one anther while heat exchange takes place between the two. In a counter-flow situation, air and liquid enter the exchanger from opposite ends. The counter flow design is more efficient, because the temperature difference between the two media is greater along any unit length. In designs illustrated in patents U.S. Pat. Nos. 3,450,393, 3,792,841, 3,952,077, and 3,963,810, the direction of the flow of heat exchange can not be easily reversed without physically changing the inner components of the cooling tower. The present invention, however, can change the flow of heat exchange by simply reversing the air cycle.
Forth, the present invention can serve due functions as a heat exchanger and as a drift eliminator or drift regulator. As mentioned previously, evaporative coolers increase moisture along with cooler air temperature in its output. Too much moisture in the air, however, can introduce other well know problems for spaces intended for human inhabitation. In some instances, drift eliminators are placed on top of the evaporative cooler to remove excess water droplets from the air existing the cooling tower. The principle of drift eliminators are illustrated in patents U.S. Pat. Nos. 4,240,814, 4,427,607, 4,557,878, and 7,105,036, where the moisture laden air is forced to change directions repeatedly. Water droplets are separated from air and left behind due to physical drag, while air passes through with less obstruction, and exits in a much dryer form. The present invention of the evaporative media module comprises multiple evaporative media units, stacked vertically on top of another. Sections of these units can be strategically sealed off at various locations, and thus force the air stream to change directions at least twice, as it passes through each unit. Such a new design not only maximize surface areas for heat exchange, but also reduce or eliminate drift from the cooler air exiting the apparatus.
Fifth, the evaporative media module of the present invention can be constructed of non-perishable material. Traditional evaporative media often incorporate soft and porous material because it can retain a larger amount of water long enough for heat exchange to take place. This type of material, however, needs to be replace from time to time to reduce bacteria or fungi growth. The present invention overcomes this problem, and thus reduce the maintenance and operational costs associated with operating the cooling apparatus.